The specific aims of this project are to understand changes and stability in memory processes associated with aging and how those changes are influenced by the person's ability to use a lifetime of prior knowledge. This project has been exploring the interface between what is known and what is new, and how this interface can be used to understand cognitive aging. People come to the lab with vast knowledge about their language. What is known, for the purpose of this project, is the lexical network each person has for the words used in the experiments. What is new is the episodic appearance of each word. The words SMELL, BOOK, LADDER, etc. may be presented in a memory experiment and everyone is familiar with and has lexical knowledge for these words. What is new in the experiment is that SMELL, BOOK, LADDER, etc. are the words to be remembered, and not other words. A major focus of the present project is to understand how activating prior knowledge affects recall and how this influence changes as adults age. We study memory using tasks in which we manipulate characteristics of the prior knowledge that is assumed to be activated. Through these manipulations we track the influence of activation on memory, observing both stable influences across younger and older adults and changing influences. We are particularly focused on three major issues: is the activation of prior knowledge as useful in prompting recall for older adults as it is for younger adults; is the utilization of prior knowledge more fragile for older adults when attentional resources are reduced; and are there age differences in inhibiting irrelevant prior knowledge? These issues have important implications for normal age changes in memory and for abnormal changes associated with dementia, particularly Alzheimer's disease. Alzheimer's can be thought of as a pathological change in memory processing that is superimposed upon the normal changes associated with aging. To understand how Alzheimer's affects memory it is essential to understand how the person would perform in the absence of the disease. This project also has implications for understanding how memory is affected by differences in the development of the mental lexicon (for example, with deaf students) or differences in the utilization of prior knowledge (as when a person has depression or substance abuse). Throughout life what is known influences what can be remembered, and understanding this influence is the goal of this project.